The invention relates to a lubricating oil composition, and in particular to a lubricating oil composition which may be used as a hydraulic fluid.
Hydraulic fluids are used for the transmission of power and control in the hydraulic systems of industrial equipment, e.g., presses, and machine tools, earth moving equipment, and marine equipment such as ship stearing gear. Above all, a hydraulic fluid should be relatively incompressible and sufficiently fluid to permit efficient transmission of power. Moreover, a hydraulic fluid must possess good lubricating properties for the pumps, bearings, etc., in the system, and should also provide good protection against corrosion, rust and wear. Accordingly, much effort has been expended in finding and improving hydraulic fluids which will meet each of these requirements.
Normally, hydraulic fluids comprise a major proportion of a base material like a lubricating oil and minor proportions of additives which possess specific properties, such as demulsifying agents, antioxidants, pourpoint depressants, anti-foam agents, VI-improvers, and additives which inhibit the rusting and corrosion of metal parts of a hydraulic system. The invention relates to such compositions.